Dunedin Mayor Dave Cull said that since Monday's announcement of the vigil - scheduled to start at 7pm tomorrow - word had reached the council that large numbers of people were expected to attend, including thousands of tertiary students.
Mr Cull said it was really heart-warming that so many people wanted to turn out.
''However, that means we're likely to outgrow the Octagon, which was the original location.
''To make sure we can include everyone who wants to take part, we need to have a really big venue and the stadium is ideal, as it can safely hold more people than the Octagon.''
The vigil, organised by the council and Amnesty Otago, was a chance for residents to ''put their arms around each other'', Mr Cull said.
It was thought up to 30,000 people could attend.
The vigil would build on an event already being organised by the Otago University Amnesty International Group, which had already been planned for tomorrow.
It would instead be a civic vigil, co-ordinated by the council.
The DCC and Amnesty had worked closely with the Muslim community and other organisations, including police, the Dunedin Multi-Ethnic Council, the Dunedin Interfaith Council and the Otago University Students' Association, in planning the event.
University staff and students will march silently to the stadium from the Memorial Bridge in Union St.
The march will leave from the bridge at 5.45pm, to walk along Union St to the stadium.
New Zealand's recently appointed chief human rights commissioner, Paul Hunt, will give a public lecture in Dunedin tomorrow morning, as part of its participation in the commission's Give Nothing to Racism Campaign.
The Otago University Students' Association will also hold a vigil tomorrow afternoon, at the bridge.
-Additionally reported by Elena McPhee
